Remote Field Bus - Metasys - LIT-12011034 - General System Information - Metasys System - Release 11.0

MS/TP Communications Bus Technical Bulletin

Product name
Metasys System
Document type
Technical Bulletin
Document number
Release 11.0
Revision date

The Remote Field Bus uses a BACnet Router to connect remote BACnet MS/TP devices to the Metasys network. These devices include CGMs, CVMs, CGEs, CVEs, FACs, FECs, VMAs, IOMs, and XPM expansion modules, ZFR Pro Wireless Gateways (WNC and WRG), the VRF Smart Gateway and Lutron Gateway, TEC36xx Series thermostats, and other BACnet MS/TP field devices. Although several routers from different manufacturers are available, the recommended device is the LIP-ME201 BACnet Router from Loytec™ Electronics GmbH. Do not use any USB-powered MS/TP to IP converter, including the Johnson Controls® BACnet to MS/TP Router (TL-BRTRP-0).

Use a Remote Field Bus for applications where connecting an RS-485 network directly to a network engine is not practical because of distance, cost, or poor accessibility. In many cases, an IP network connection is available at both the network engine and at some point near the BACnet MS/TP devices. By leveraging the Metasys Remote Field Bus capability with installing the BACnet Router near the BACnet MS/TP devices, you can reduce system cost. Also, when you choose MS/TP device integration with a router rather than BACnet Integration, access to proprietary attributes, message types, and objects from Metasys equipment controllers is available. This functionality provides you with more information and more capability than the standard BACnet attributes, services, and object types. For example, at the Site Management Portal you can view proprietary attributes such as communication statistics from mapped Metasys equipment controllers. Also, remote MS/TP device integration supports the CCT Passthrough option for downloading devices directly connected to the Remote Field Bus (but not to devices connected to the sensor bus).

Figure 1 shows an example of a Metasys network with a Remote Field Bus.

Figure 1. Example of a Remote Field Bus

The Remote Field Bus is defined at a Metasys network engine or OAS Workstation (Figure 2) through field bus integration, similar to how a local MS/TP field bus is added. The Remote Field Bus appears on the All Items Navigation tree in the Site Management Portal UI. You can also provide a custom name to clearly identify the type of integration.

Note: To ensure acceptable system performance, make sure that you map all devices and objects that originate from a Remote Field Bus to a single network engine, for example, if you have two SNEs (SNE-1 and SNE-2), each with a separate Remote Field Bus. Device 1 is defined under SNE-1, and Device 2 is defined under SNE-2. In this arrangement, make sure you do not map Device 1 to SNE-2 or map Device 2 to SNE-1. If you mix remote field device mapping between supervisory engines, the Metasys system may start very slowly, and devices may have difficulty staying online.
Figure 2. Example of a Remote Field Bus with OAS

Applications for the Remote Field Bus include:

  • Any intra-building, inter-building, or remote location that has IP network connections readily available
  • Locations where it is cost prohibitive or difficult to run MS/TP wiring between devices and the supervisory engine, due to distance, cost, accessibility, or customer factors
  • Locations where equipment controllers are segregated from the network engine
  • Intra-building applications that connect segregated locations within a building (for example, connecting penthouses to mechanical rooms)
  • Remote buildings where an MS/TP bus is not already available, but an Ethernet BACnet/IP network is (for example, university or hospital campuses)
  • Sites with a reliable network between buildings that do not need to have a separate SNE or NAE for the building (for example, school districts)
Note: The ZFR1800 Series Wireless Field Bus System is not supported on the Remote Field Bus.

For details on how to add a Remote Field bus, refer to the MS/TP Field Bus Integration Object section in Metasys SMP Help (LIT-1201793). For details about how to add a Remote Field Bus to a Metasys network engine with an ODS, refer to the ODS Commissioning Guide (LIT-12011944). For details on the VRF Gateway, refer to the VRF Smart Gateway User's Guide (LIT-12012385).

Additional background on the Remote Field Bus is covered in the following sections: